Two summers ago, at a consumer-electronics show in Chicago, Sega Enterprises Ltd. trumpeted its plans for a $200 virtual-reality game system based on its popular Genesis machine. Then, Sega managers got the results of a study they had commissioned from researcher SRI International in Menlo Park, Calif. By Christmas, the VR project had been shelved, never to be revived.
Neither Sega nor SRI will discuss details of the study. Steven Payne, Sega's vice-president for product development, says only that the machine "couldn't deliver the experience we wanted." But word quickly leaked out that some users who donned Sega's prototype head-mounted display (HMD) suffered jarring symptoms, from nausea to sore eyes--a suite of complaints the VR community calls "cybersickness."
These side effects were no sudden revelation. After 30 years of experience with VR for flight and weapons training, the U.S. military today often grounds pilots who experience queasiness during simulations--a condition it calls "simulator sickness." Nonetheless, Sega's retreat sent a chill through the young VR industry, which wants to bring virtual entertainment into every home.
Now, as a wave of VR products approaches the consumer market, manufacturers of HMDs, gloves, and PC add-on boards fear that eye injuries or LSD-style "flashbacks"--and ensuing litigation--could hobble the budding VR market. "I'm worried about long, unsupervised use by children," says Gordon Kuenster, CEO of headset maker Virtual Image Displays Inc. (VIDI) in Redmond, Wash. Adds McGill University psychologist Glenn F. Cartwright in Montreal: "There could be some big lawsuits looming."
MIXED SIGNALS. Lack of clinical data makes it hard to pinpoint causes of cybersickness, but there are several theories. Users may strain their eyes squinting at low-resolution screens. Sharper displays help but aren't a panacea. Most HMDs focus the eyes at a flat depth, then create a 3-D illusion of objects moving closer and farther away, which sends conflicting signals to the brain. "That's not natural," says University of Edinburgh psychologist John Wann, who studies VR-related complaints. Queasiness has a different cause. Experts trace it to corruption of a mechanism called the vestibulo-ocular reflex, which the brain uses to coordinate input from the eyes and the inner ear. If a VR system processes visual information too slowly, says Joshua Larson-Mogal, market-development manager at Silicon Graphics Inc.'s Advanced Systems Div., the two sets of signals get out of synch. For example, the inner ear will signal that a users' head is turning. But it takes a split second for the visual imagery to catch up--a factor called latency.
To Larson-Mogal, the solution is obvious: lightning-fast processing speed from a high-end SGI workstation. But in fact, latency isn't always the culprit. After studying high-performance simulation for 10 years, Dennis K. McBride, the Office of Naval Research's chief scientist for modeling and simulation, found that experienced pilots are most vulnerable to VR side effects when using the most realistic flight simulators.
In this case, by being immersed in simulation that lacks physical effects such as inertia, "the pilot has opened up other neural pathways in the brain, different from what is used in real flight," says VR pioneer Thomas A. Furness, director of the Human Interface Technology Lab at the University of Washington in Seattle. That creates conflict and can result in flashbacks hours or even days after the simulation is over.
SECRET STUDIES. Probing cybersickness is tough because the experience is so subjective. And each symptom probably has multiple causes, which in turn spawn multiple side effects, says Dr. Robert Kennedy, a vice-president at Essex Corp. in Columbia, Md., which investigates "human factors" for the military. With the same experience, "one person may end up with nausea and another with strained eyes," he says. Unfortunately, much of the research to date was sponsored by private companies that refuse to share it. The result: "Designers can't correct for mistakes that have already been made by other companies," says Edinburgh's Wann.
Perhaps because the complex fabric of afflictions is so poorly understood, no government agency even attempts to regulate VR gear. But private companies are trying to head off potential complaints. In developing lightweight VR goggles called i-glasses, Seattle-based Virtual i-O Inc. deliberately left clear viewing space around and under the image projected in front of the eyes. "Almost nobody experiences nausea," says President Linden Rhodes. Likewise, VIDI's single-eye device lets the user keep tabs on ordinary reality.
To purists, these solutions fall far short of the full-immersion experience. The largest players are spending big bucks to resolve health issues without compromising. In Japan, Sega engineers have readied a new HMD. Paired with the powerful, 32-bit Saturn machine Sega just released in the U.S., it will deliver a "knock-your-socks-off experience," Payne says. Japanese game fanatics are already testing a version of it in arcades in Tokyo. Sega is mum on the U.S. launch. But Payne promises "a battery of new [health] tests" before releasing a consumer version here.
Sega isn't alone. Working with SGI, Walt Disney Co. spent upwards of $4 million on the experimental Aladdin Magic Carpet Ride at Disney World's Epcot '95 in Orlando, Fla. SGI's Larson-Mogal calls it "the most effective, comfortable VR system" he has tested. It is also the most closely monitored. Since the exhibit opened last July, each of the 35,000-40,000 "riders" has filled out a survey, including details on side effects. The results? "It's right in the range of a roller coaster or other thrill rides," says virtual-reality studio co-director Jon Snoddy, who observes the riders on live video from his office at Disney headquarters 3,000 miles away. Snoddy doesn't fret about people getting sick on verisimilitude, like the fighter pilots, because "for most people, reality doesn't include flying carpets."
Even some researchers whose work has set off international alarm bells think the rewards society will reap from VR will outweigh the risks. At Britain's University of Nottingham, Virtual Reality Applications Research Team director John R. Wilson has spent four years studying VR hazards, supported by the governmental Health & Safety Executive. In a report last year probing VR woes, he also listed benefits the technology bestows, including ergonomic assessments of workplaces, engineer training, and surgical applications.
But Wilson doesn't repudiate the litany of users' physical complaints. And as VR spreads through society, these may be just the beginning. Computer networks let users change their personalities, backgrounds, and genders in cyberspace. It's the stuff of science fiction, but virtual reality will let them flesh out these alternate personae and project these creations into virtual bodies or any other virtual space. "This is a totally new phenomenon," says McGill's Cartwright. "It may bring new kinds of emotional disturbances and mental illnesses." Long before that happens, however, manufacturers will have to grapple with complaints--and litigation--that are just around the bend.
VIRTUAL REALITY MAY BE HAZARDOUS TO YOUR HEALTH
The next big splash about VR could come from lawyers. Low-end systems may pose risks:
Squinting at low-resolution images in a cheap head-mounted display (HMD) can strain your eyes. So can poorly crafted spatial illusions. Some doctors suggest limiting exposure to one hour.
Nausea and confusion occur when head position and visual signals are out of synch. Effects vary with individuals but appear most likely with low-end systems that display less than 60 frames per second.
Virtual reality creates audio and visual illusions of motion but lacks other physical cues. To resolve the conflict, the brain forges new neural pathways, which can cause flashbacks hours later.